Hey i have a check engine light and was wondering what could be causing the issue. I replaced everything already besides a few other things i could think of witch ill try today but any way the CEL light is

P0171 Bank 1 system too lean

P0546 I believe its a EGT SENSOR

its a 02 wrx bugeye with a 05 sti swap it was running like crap before i changed the oil and spark plugs and what im thinking of changing today is a fuel filter and air intake filter since its not stock and the car also has a front mount

i was wondering if the front mount is a bad idea its not tuned for the front mount and its not tuned for the intake i just got the subie and wanted to get rid of the check engine light so i can cruz and not worry about the check engine light.

Are the CELs a new thing, or have you had the issues since you bought the car?Any issues with the car's performance? If so, what is it doing (other than the cel)?What exactly did you replace?Any other mods on the car other than the front mount and intake? Downpipe perhaps?

Another thing when I first had the Subaru it had no O2 sensors and the cel light was already on so I took it to autozone to see what was causing the cel and it gave me 2 codes at first the front and rear O2 sensors

I replaced those and it ran like crap after swapping the new o2s in cel light came back went to check and it gave me 7 codes all cylinders were misfiring and runing too lean and the egt

Did a tune up on it changed spark plugs new oil and it took care of the misfireing and only put out 2 codes after the tune up witch was the same two I posted about I fixed the egt by putting the resistor on it and it went away now I'm stuck with the P0171

What I'm going to do tomorrow is buy a new fuel filter and possibly a air filter it looks really dirty and clean the maf

Any idea how I can vacuum leak test it or know anyone with a device I can try on it any help is appreciated and also just what I know of the car